Fusible cut-out



D. RNNBERG FUSIBLE CUT-OUT June 4, 1935.

Filed June 2l, 1933 2 Sheets-Sheet l FigQ Vw 8 I/ f f /v INVENTFL BY/Qm June 4, 1935. D RNNBERG 2,003,977

FUS IBLE CUT OUT Filed June 2l, 1935 2 Sheets-Sheet 2 /H Ven Z107@ cm e Z Rm/2 @erg Patented June 4, 1935 UNITED STATES PATENT OFFICE FUSDSLE CUT-OUT Application June 21, 1933, Serial No. 676,793 In Sweden June 22, 1932 5 Claims.

The present invention has for its object a fusible cut-out in Which the arc that appears when the fuse metal blows is extinguished by a stream of gas or liquid. The invention is characterized thereby that this stream of gas r liquid is set in motion by a differential piston, which is movable in a double cylinder of insulating material surrounding the fuse metal. This cylinder is divided by the differential piston into two compartments connected by a channel which is traversed by the gas or liquid when the piston is moving. The fuse metal strip or wire is also drawn through this channel. The motion of the differential piston is accomplished by the pressure generated by the arc that appears when the fuse blows.

In the accompanying drawings, two forms of the invention are shown. Fig. 1 is a longitudinal section showing one form of the invention, and Figs. 2 and 3 are longitudinal sections showing two slightly altered forms.

In Fig. l, I designates a cylinder of insulating material, for instance synthetic resin material or porcelain, It is closed by metal covers 2 and 3 at the ends and these covers are connected to metal terminal ferrules 4 and 5. The cover 2 is formed to a cylinder 6, in which one end of the differential piston 'I moves. The other end of the differential piston is provided with a iiange 8 moving in the outer cylinder I. The fuse metal 9 which has a weak portion is inserted between a clamp I0 on the piston 'I and the flat I3 of the ferrule just inside the cover 3. The clamp ID is provided with a flexible conductor EI connected to the cover 2. The piston 'I is provided with a channel I4 through which the fuse metal 9 is drawn. As long as the fuse metal is intact, the piston I is pressed by it against the shoulder I1?, but when the metal blows an arc appears between the heavy strips I5 and i6, which develops chieiiy in the lower compartment il. The gas generated by the arc-or Vapor if the cylinder is filled with a liquid-will exert an upward pressure on the piston '1. When this has been released by the blowing of the fuse metal, it will be forced upwards and thereby decrease the volume of the compartment i 8, so that the gas or liquid will flow from this compartment through the channel I5 thereby effectively cooling the arc, which also traverses the channel.

The fusible cut-out can either be filled with oil or with air or some other suitable gas or liquid.

In Fig. 2 another form of the invention is (Cl. 20D- 120) shown in which corresponding parts are designated with corresponding figures to those used in Fig. l. This form differs from that of Fig. l only in that the upper part of the differential piston 'I moves in a cylinder 5 communicating 5 with the atmosphere. The compartment that is diminished by the motion of the piston and from which liquid or gas is escaping is annular and surrounds the upper part of the piston, which is provided with channels I9. The fuse metal 10 is fastened at the lower end to a spring which, when the metal blows, rapidly draws out the arc, so that even at small currents a sufficient pressure can arise. The function of this form is in other respects quite the same as the func- 15 tion of the form shown in Fig. 1.

Fig. 3 shows a form of the invention similar to that shown at Fig. 1 but with provision whereby the piston may also partly be actuated by a spring 2I which is held in compression by the 20 fuse metal I5 but is released when the latter blows. The piston 8 will be acted on by the force of the spring 2I plus the force exerted by the generated gas.

I claim as my inventionz- 1. A fusible cut-out comprising a double cylinder, differential surfaces within said cylinder, a differential piston engaging both said surfaces and dividing the space inside said cylinder into two compartments, a channel in said piston connecting said compartments, a fuse metal strip extending through said channel, an arc extinguishing medium in said cylinder a stream of which is forced through said channel by the motion of the piston.

2. A fusible cut-out comprising a double cylinder, differential surfaces within said cylinder, a terminal at each end of said cylinder, a differential piston engaging both said surfaces and dividing the space inside said cylinder into two compartments, a channel in said piston connecting said compartments, a fuse metal strip passing through said channel and fastened at one end to said piston the ends of said metal strip being connected to said terminals.

3. A fusible cut-out comprising an insulating cylinder, a terminal at each end of said cylinder, a second cylinder mounted inside said cylinder, differential surfaces within said cylinders, a differential piston sliding against said surfaces and dividing the space inside the outer cylinder into two compartments, a channel in said piston connecting said compartments, a fuse metal strip passing through said channel and fastened at one end to said piston, the ends of said metal strip being connected to said terminals.

4. A fusible cut-out comprising a double cylinder, differential surfaces Within said cylinder, a differential piston engaging both said surfaces and dividing the space inside said cylinder into two compartments, a channel in said piston connecting said compartments, said channel being formed in an insulating Wall of said piston, a fuse metal strip extending through said channel, the main part of said stripy being in the' compartment bounded by the larger end of the piston.

5. A fusible cut-out comprising a double cylinder, differential surfaces within said cylinder,

a differential piston engaging both said surfaces and dividing the space inside said cylinder into two compartments, achannel in said piston connecting said compartments, said channel being formed in an insulating Wall of said piston, a fuse metal strip extending through said channel, the main part of said strip being in t'ne compartment bounded by the larger endV of the piston, a 10 Weak portion in the strip 0n said part.

DANIEL RNNBERG. 

